MTN Debit Orders... MTNs problem

I have performed an Upgrade in November 2020. Ever since i have to beg MTN every month to Debit my account. When i ask to speak to a teamleader or manager, i am promised that they will call me back, cos everytime they are not available. Tried over 5 times to speak to a teamleader and manager... and still waiting for there call. Why must i continuously call MTN 135 wait about 15mins to speak to a consultant and ask them to debit my account. If i dont do this.. will MTN then threaten to Black List me for there mistake ??? You cant even find a contact number for a HeadOffice or Manager to speak to...